Osprey’s Mutant series of packs have nothing to do with turtles but may well have something to do with ninja’s – the alpine variety.

The Mutant series, now in its 5th generation is specifically designed for climbing and mountaineering. I would have loved to have tested its full capabilities with some climbing action but on the weekend just gone I had an opportunity to test it out on a caving trip down the West Coast of Tasmania near Lake Mackintosh where limestone karst has hollowed out literally hundreds of caves where a local caving team have been meticulously documenting their locations, sizes and features now for a number of decades. A few outliers remained unverified because of their distance and challenging terrain to access. These were our targets for the weekend and the Mutant 22 was put through its paces.

Design & Durability (Rating: 90%)

The Mutant series of “Technical Packs” comes in three sizes – 52L, 38L, and the 22L that I tested. They come in two colour options – Black Ice (black with blue accents) and the awesome Blue Fire (navy blue with orange accents).

Features of the 22L include:

  • Snowshed fabric back panel
  • Dual ToolLocks with bungee tie-offs
  • Front panel daisy chain for additional gear attachment
  • Three-point haul system
  • Internal hydration sleeve
  • Glove-friendly buckles
  • Inside/out rope attachment, internal compression
  • Removable webbing hipbelt
  • Storage pocket under large top-zip opening for storing smaller items with key clip
  • Side loops for additional compression or attachment points


The 52L and 38L packs include other features such as removable top lid and hip belt for stripping excess weight and the design of the packs are very focused on streamlining for alpine climbing with enough gear attachments to get you to the top of a climb without being so feature-rich that there are snag points and bulk to slow you down.

There are no external pockets for this reason and internally there is a small pocket just under the lid. This conforms to the streamlined design of the pack. There are however interesting bungee gear attachment points for ropes and ice axes and in my case walking poles would have attached conveniently had I chosen to take them. I was able to use the tie off points to carry a climbing helmet. The fabric is tough 210D High Tenacity Nylon with 420D Nylon Packcloth on the bottom.

The Mutant uses a framesheet of corrugated stiff foam which is removable but serves to give just enough stiffness, while maintaining the pack close to the body (some packs try and hold the pack away from the body to allow for air circulation which you don’t want when climbing) but with corrugation to allow for breathability.

A couple of other features are worth a mention. Osprey once used a sliding chest strap adjustment. Not a bad idea as it allows for infinite up and down increments but allowed the chest strap to ultimately slide right off. On the mutant, they’ve used a system of button holes so you can adjust the strap up and down by selecting the hole and threading the webbing through whichever one you wish. The other feature I like is the two daisy chain webbings running down the outside of the pack where you can clip biners onto and attach pretty much whatever gear you want. It’s a much neater solution that the loops provided on most packs which hang out and snag easily.

Oh, did I mention it’s light? Really light in comparison to my other bomb proof Snowgum day pack. The Mutant weighs in at a paltry 0.6 Kg.

Osprey Mutant 22L Backpack Review

Functionality & Ease of Use (Rating: 95%)

I stuffed a fairly large first aid kit (I’m a ‘firstaiderphile’ – new word, but we’re more common than you think), snake bandages, waterproof jacket, 3L of water into the hydration sleeve, go pro and accessories, DSLR, snacks, toilet gear, and a helmet on the outside and I still had room to spare (which I didn’t let on to the others because it was gruelling enough without carrying slings, ropes, steel ladders and biners). I swung the pack on without realising it had a hip belt, adjusted the chest strap and away I went. We travelled through some pretty sketchy steep terrain which was so scrubby that much of the time we used downed mossy logs to “snake and ladder” our way through rainforest that some years ago had suffered bushfire downing many of the trees and allowing for ferocious undergrowth.

What really impressed me was how snug the pack hugged my back. Usually when lunging sideways, stumbling through thick scrub with logs and branches hidden underfoot a pack would normally sling from side to side adding to the balance problems but the mutant seemed to be designed in such a way that without feeling tight, it just hugged the back. It was so streamlined and well designed it just fit my body and without even doing up the hip belt it didn’t move side to side at all. I’ll probably just remove it.

I was using gloves from time to time for roping or scrub bashing and the big rubberised loops on the top lid zips were brilliant for being able to use with gloves on.

What I Like

  • It fits like a charm and just doesn’t move even without doing up the hip belt.
  • The fabric is tough and slick to shed water, snow and dirt.
  • Just enough gear attachment points without introducing unnecessary snags.
  • The narrow alpine design is built for speed. Clambering under logs and through storm-downed celery pine branches I didn’t hang up once.
  • I thought the 22L wouldn’t be big enough for the gear required for 10 hours of hiking and caving but I was wrong. It’s ideal for a day trip.
Osprey Mutant 22L Backpack Review

What I Don’t Like

  • The pocket inside the lid could have been a bit bigger without compromising anything. This is the ideal spot for say a GPS, your keys – small items that you want to get to without having to empty your whole pack because the item made its way to the bottom.
  • I lost my helmet which was attached to the rope bungee loops but this was because I didn’t get enough stretch on the loops so a little user error there, and the loops were intended for ropes which would give them plenty of stretch.
  • The pack is designed to stick with some degree of breathing on the back but with the level of exertion I was putting out, nothing was going to keep my back dry – but it dried pretty quickly when I stopped and took the pack off.

Get One

The Osprey Mutant 22L Backpack is available online from Wild Earth.

Disclaimer: Osprey provided a backpack for review. The above purchase link is an affiliate link. This has no impact on the opinions presented in the review.

Have you tried the Osprey Mutant 22L Backpack? Got any questions or comments? Let us know by commenting below.